Experimental drug APN01 prevents COVID-19 infection in the lab

By Dr. Ananya Mandal, MDApr 6 2020

With the world gripped with the COVID-19 pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), there is a frantic rush to find an effective drug that can be used to treat the disease.

Researchers from the University of British Columbia, in collaboration with others, have found an experimental drug that can inhibit the SARS-CoV-2 virus from infecting host cells. Their study titled, "Inhibition of SARS-CoV-2 infections in engineered human tissues using clinical-grade soluble human ACE2," was published in the latest issue of the journal Cell.

In cell cultures analyzed in the current study, hrsACE2 inhibited the coronavirus load by a factor of 1,000-5,000. Credit: IMBA/Tibor Kulcsar

What were the highlights of the study?

As of today, 6^th April 2020, the virus has affected 1,341,907 individuals worldwide and killed 74,476. Many of these deaths were caused by severe lung injury.

Dr. Josef Penninger, study leader, and his team are working on ways to inhibit SARS-CoV-2's capacity to infect human host cells. They write that in their previous study, they had explained the mechanism of infection caused by this virus and how angiotensin-converting enzyme 2 (ACE2) receptor plays a vital role in the infection. The enzyme ACE2 has the capacity to protect the lungs from injury caused by the virus. This also provided an explanation regarding the severe lung damage, respiratory failure, kidney and blood vessels, and eventual death seen in some of the individuals.

The team wrote that the ACE2 receptor and the SARS-CoV-2 interaction could be one of the critical areas for drug targets since this is vital for the virus to infect the human host cells. They speculate that human recombinant soluble ACE2 (hrsACE2) could be vital to block the invasion of the host cell by the SARS CoV-2.

Penninger, a professor at UBC's faculty of medicine, director of the Life Sciences Institute and the Canada 150 Research Chair in Functional Genetics at UBC, said, "We are hopeful our results have implications for the development of a novel drug for the treatment of this unprecedented pandemic." He added, "This work stems from an amazing collaboration among academic researchers and companies, including Dr. Ryan Conder's gastrointestinal group at STEMCELL Technologies in Vancouver, Nuria Montserrat in Spain, Drs. Haibo Zhang and Art Slutsky from Toronto and especially Ali Mirazimi's infectious biology team in Sweden, who have been working tirelessly day and night for weeks to better understand the pathology of this disease and to provide breakthrough therapeutic options."

What was done?

Penninger and his team from the University of Toronto and the Institute of Molecular Biology in Vienna tried to find the link between cardiovascular disease, lung damage, and the protein. They explained that at present, there are no antiviral drugs that can definitively kill the virus, and this new approach could be the only option.

Dr. Art Slutsky, a scientist at the Keenan Research Centre for Biomedical Science of St. Michael's Hospital and professor at the University of Toronto, who was part of this study explained, "Our new study provides very much needed direct evidence that a drug -- called APN01 (human recombinant soluble angiotensin-converting enzyme 2 - hrsACE2) -- soon to be tested in clinical trials by the European biotech company Apeiron Biologics, is useful as an antiviral therapy for COVID-19."

APN01 is a recombinant human Angiotensin Converting Enzyme 2 (rhACE2) under Phase-2 clinical development in ALI (Acute Lung Injury) and PAH (Pulmonal arterial hypertension). Recently, ACE2 has been shown to be the cellular entry receptor for the novel coronavirus SARS-CoV-2. Therefore APEIRON initiated now a clinical Phase II study in Austria, Germany, and Denmark for treatment of COVID-19 and is planning a clinical study in China in patients infected with SARS-CoV-2. APEIRON Biologics AG.

For this study, the team used biomedically engineered organoids in the lab that mimicked human blood vessels and kidneys. These are essentially clumps of cells that act as the whole organ within the human body and are grown from human stem cells. On these organoids, the team then used hrsACE2 and found that it could prevent the entry of the coronavirus into the host cells. The decrease in the viral load affecting the host cells was by a factor of 1,000-5,000, they wrote.

Núria Montserrat, ICREA professor at the Institute for Bioengineering of Catalonia in Spain, part of the team, added, "Using organoids allows us to test in a very agile way treatments that are already being used for other diseases, or that are close to being validated. In these moments in which time is short, human organoids save the time that we would spend to test a new drug in the human setting."

For this study, they used a Swedish patient who tested positive for COVID-19 in early February 2020. The SARS-CoV-2 virus was isolated from the nasopharyngeal samples of the patient. They grew the virus in the Vero E6 cells and looked at its genetic sequence using Next-Generation Sequencing (Genbank accession number MT093571).

What was found?

The researchers wrote, "Here we show that clinical-grade hrsACE2 reduced SARS-CoV-2 recovery from Vero cells by a factor of 1,000-5,000." They added that using an equivalent of mouse rsACE2 on the cells had no such inhibitory effect of the virus on the human organoids. They add, "We also show that SARS-CoV-2 can directly infect engineered human blood vessel organoids and human kidney organoids, which can be inhibited by hrsACE2."

They wrote, "hrsACE-2 can inhibit SARS-CoV-2 infection in a dose-dependent manner hrsACE2 has already undergone clinical phase 1 and phase 2 testing and is being considered for the treatment of COVID-19."

For this study, they found the efficacy of clinical-grade hrsACE2. They infected the Vero-E6 cells with different viral loads of SARS-CoV-2. They named them "103 plaque-forming units (PFUs; MOI 0.02), 105 PFUs (MOI 2), and 106 PFUs (MOI 20)," respectively. Infection of cells after an hour of administration of hrsACE2 followed by washing and incubation without hrsACE2 showed that at 15 hours post-infection, there was a significant SARS-CoV-2 infection in the cells. They tested the viral RNA in the cells using qRT-PCR.

Conclusions and implications

Penninger added, "The virus causing COVID-19 is a close sibling to the first SARS virus. Our previous work has helped to rapidly identify ACE2 as the entry gate for SARS-CoV-2, which explains a lot about the disease. Now we know that a soluble form of ACE2 that catches the virus could be indeed a very rational therapy that specifically targets the gate the virus must take to infect us. There is hope for this horrible pandemic."

The team concludes that as such, it cannot be predicted that the effects of the hrsACE2 would remain the same during the whole course of the illness. What can be seen is the prevention of the virus from infecting host cells, they wrote. They also warn that this study did not test the effect of the trial drug on lung organoids, and as lungs are one of the main organs that are damaged, the study needs further exploration. Also, human trials are needed to see the effect of the drug on actual patients of COVID-19. They sign off, "To address these issues, further studies are needed to illuminate the effect of hrsACE2 at later stages of infection in vitro and in vivo."

The study was funded by the Canadian federal government.